Telephone-exchange system.



A. E. LUNDELL.

TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED JULY 5,1916.

Patented Nov. 6, 1917.

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UNITED STATES PATEN '11 FFEQEQ ALBEN E. LUNDELL, OF NEW YORK, N. Y.,ASSIGNOR TO WESTERN ELECTRIC COMPANY INCORPORATED, OF NEW YORK, N. 1., ACORPORATION OF NEW YORK.

TELEPHONE-EXCHANGE SYSTEM.

Application filed July 5, 1916.

To all whom it may concern:

Be it known that 1, Annex E. LUNDELL, a citizen of the United States,residing at New York, in the county of Bronx and and State of New York,have invented certain new and useful Improvements in Telephone-ExchangeSystems, of which the following is a full, clear, concise, and exactdescription. 7

This invention relates to telephone eX-. change systems, and moreparticularly to systems in which machine switching is employed.

An object of this invention is to provide simple testing means for theswitches at the ends of a double switch-ended trunk.

An additional object of the invention is to provide simple testing meansfor hunting switches in a system in which means are provided forindicating to an operator the class of service to which a callingsubscriber is entitled.

In a well-known type of class of service indicating device, a highvoltage battery is used, its purpose being to intermittently sendimpulses to operate an indicating device. If a hunting finder should bepassing over the terminals of a line at the instant an impulse is beingsent by the class of serrice indicating device of such line, the testrelay of the finder would be energized and the finder would stop on theterminals of a non-calling line, unless means are pro vided to preventsuch action.

A feature of the invention is the use of a single test relay to controlboth the line finder switch and the cord selector switch of a connectingcord circuit.

A further feature of the invention is a relay having a double winding,themagnet-ic effect of these windings being differential when the brushset of a finder is passing the terminals of a non-calling line at theinstant an impulse is being sent by the class of service indicatingdevice of such line.

A still further feature of the invention is the provision of a centeringbrush which is in electrical connection with a commutator segment at thetime the brushes are centered on a terminal set,-the circuit of suchcentering brush being through one winding of a test relay.

In the embodiment shown the finder switches, cord selector switches andcon- Specification of Letters Patent.

Serial No. 107,551.

trolling sequence switches may be of the type disclosed in Patent No.1,168,319, issued January 18, 1916 to Alben E. Lundell.

It is thought that the invention will best be understood from thefollowing detailed description, reference being had to the accompanyingdrawing.

In the drawing, the portion to the left of the dotted line indicatesschematically the substation apparatus of a calling subscriber and aconnecting cord circuit including a line finder switch anda cordselector switch. The portion ofthe drawing to the right of the dottedline indicates an operators cord circuit and the substation apparatus ofa called subscriber. 7

When the subscriber at substation S desires a connection, he removes hisreceiver from the hook, whereupon line relay 1 is energized inthe-well-known manner and closes a circuit for relay 2 from groundedbattery A, contact 3, lamp 8, armature and front contact of relay 1, andthe winding of relay 2, to ground, provided that conta' t 3 is closed atthis time. If contact 3 is open, contact 6 W111 be closed as will belater described, and the circuit of relay :2 under this condition isfrom grounded battery B, contact 6, resistance 7, lamp 8, to ground overthe path just traced. Relay 2 is energized and attracts its armature,closing a circuitv from ground, armature and front contact of relay 2,sequence switch contact 102, and the winding of power magnet 100 of theconnecting cord sequence switch SS, to grounded battery A. The sequenceswitch SS moves from position 1 to position lunder the con-' trol of itsnormal contact 101. its the sequence switch SS passes through position 2and comes to rest in position 4, a circuit is closed from groundedbattery A, winding of lip-drive magnet 103, sequence switch conk tact10%, to ground at the right-hand armature and back contact of test relay105. Under the control of magnet 103, a brush set 106, 107, 108, 109 anda centering brush 110 are moved upward, the brush set passing overterminal sets 111, 112, 113, 114 and the centering brush passing over acommutator strip 115.

At this time it mightbe well to describe the operation of a device fortransmitting impulses to a class of service indicating means at anoperators position, suchdevice Patented Nov. 6, 1917.

being indicated at 4 and 5. 1 and 5 are coir stantly rotating camsoperating spring contacts 3 and 6. The relation of the cams and switchsprings is such that just before contact 3 is opened, contact 6 isclosed. Ii we assume now that battery A is of low voltage, for instance,twenty-four volts, and battery B is of high voltage, for instance,forty-eight volts, an in pulse of high voltage will be transmitted toterminal 111 on each revolution of the shaft driving the cams 1 and 5,the circuit being from grounded battery 13, contact resistance 7, lamp8, conductor 9, to terminal 11. By suitable arrangement and cutting ofthe cams 4 and 5, any desired number of impulses per revolution may besent.

WVhen the brush set 106, 107, 108, 109 arrives on the terminals or thecalling line, a circuit is closed from grounded battery, lefthandwinding of relay 105, sequence switch contacts 116, 117, conductor 118,brush 106, terminal 111, conductor 9, armature and front contact ofrelay 1, winding of relay 2, to ground. When the brush set is centeredon the terminals, a parallel circuit is closed from grounded battery A,right-hand winding of relay 105, resistance 119, sequence switch contact120, a conducting segment of commutator 115, and brush 110, to ground.The windings of this relay are so arranged that the energy suppliedthrough the righthand winding and the circuit just traced, isinsufficient to operate the relay, but when in addition, energy issupplied to the left-hand winding through the circuit previously tracedwhen the wiper 106 comes in contact with the terminal 111 of the callingline, it is sufficient to operate the relay 105. Relay 105 thereuponattracts its armatures, opening at its right-hand armature thepreviously traced circuit of the up-drive magnet 103, thus causing thebrush set to come to rest on the terminals of the calling line. At itsleft-hand armature and front contact, relay 105 establishes a lockingcircuit for itself from grounded battery A, left-hand windin andleft-hand armature and front contact of relay 105, sequence switchcontact 121, brush 107, terminal 112, and cut-0E relay 10, to ground.Message register magnet 15 is included in the parallel branch of thiscircuitbut is not energized at this time since it is marginal and willnot energize in series with a resistance when subjected only to currentfrom low voltage battery A.

Cut-off relay 10 is energized in this cir cuit and remains energizeduntil the conclusion of the conversation, its circuit being maintainedwhile the sequence switch is moving from positions 4:3 to 10 by sequenceswitch contact 155 over a circuit from grounded battery A, resistance156, sequence switch contact 155, brush 107, terminal 112, winding ofrelay 10, to ground. In positions 10 to 1st of the sequence switch SS,relay 10 is maintained energized in series with a relay 139, as will bedescribed later.

It should be noted at this point that if the brush set passes theterminals oi a non-calling line at the instant a high voltage impulse isbeing sent by the class of service impulse transmitting device C, acircuit will be closed from high voltage battery B, contact 6,resistance 7, lamp 3, conductor 9, terminal 111, brush 100, conductor113, sequence switch contacts 116, 117, left-hand winding of relay 105,to low voltage battery A, to ground. This current, however, flowsthrough the left-hand winding of relay 105 in a direction such that themagnetism set up by said current opposes that set up through theright-hand winding of relay 105, by the engagement of centering brush110 with a conducting segment of commutator strip 115. Relay 105 will,therefore, not be encrgized and the brush set will pass the tcrminals ofsuch undesired line.

When relay 105 attracted its right-hand armature, a circuit was closedfrom ground, through the right-hand armature and front contact of relay105, sequence switch contact 122, and the winding of power magnet 100 togrounded battery A. The energization of power magnet 100 moves thesequence switch from position at to position 9.

lVhen the sequence switch leaves position 4-, the circuit of theright-hand winding of relay 105 is broken at sequence switch contact120, and when the sequence switch leaves position 13;, the lockingcircuit of relay 105 through its left-hand winding is broken at sequenceswitch contact 121. Re lay 105 is deenergized and releases itsar1natures.

sequence switch SS passes through position 8, a circuit is closed fromgrounded battery A, through the winding or" up-drive magnet 123,sequence switch contact 12 1, to ground at the righthand armature andback contact of relay 105. Under the control of the up-drive magnet, thebrushes 125, 126, 127, 123 of a cord selector are moved upward overterminal sets 129, 130, 131, 132. A centering brush 133 is also carriedupward by the brush carriage and moves over a commutator segment 13%.When the brush set arrives on the terminal set of an idle cord, asindicated by the presence of ground on the test terminal 129, a circuitis completed from grounder battery A, through the left-hand winding ofrelay 105, sequence switch contacts 116, 135, conductor 136, brush 125,terminal 129, and operators sequence switch contact 200, to ground. Acircuit is also completed from grounded battery, through the right-handwinding of relay 105, resistance 119, sequence switch contact 137, aconducting seg ment of commutator 134-, and brush 133, to

ground. Relay 105 thereupon attracts its armatures, completing, at itsright-hand armature and front contact, a circuit from ground throughsequence switch contact 122 and the winding of power magnet 100, togrounded battery, for moving the sequence switch out of position 9 andinto position 14. WVhen relay 105 attracted its righthand armature, itbroke the circuit of the up-drive magnet 123 which deenergizes andallows the brush set to come to rest on the desired terminal set.

lVhen the cord selector CS came to rest on the terminals of an operatorscord circuit, a circuit was completed from grounded battery, powermagnet of sequence switch 210, contact 212, terminal 131, brush 126,relay 139, contact 138, brush 107, terminal 112, winding of cut-offrelay 10 to ground, for moving the operators sequence switch 210 fromposition 1 to position 7, under the control of its normal contact 211.

In position 7 of the operators sequence switch SS, a circuit is closedfrom ground, winding of cutoff relay 10, terminal 112, brush 107,sequence switch contact 138, the winding of relay 139, brush 126,terminal 130, operators sequence switch contact 201, spring contact 202of relay 209, and the winding of a relay 203, to grounded battery A;Relay 139 is energized and remains energized until the conclusion of theconversation. Relay 139, in energizing, completes an impulse circuit aspreviously described, from grounded high voltage battery B, contact 6,resistance 7, lamp 8, conductor 9, terminal 111, brush 106, conductor118, left-hand armature and front contact of relay 139, sequence switchcontacts 140, 135, conductor 136, brush 125, terminal 129, operatorssequence switch contact 204, key 205, and the winding of relay 206, togrounded low voltage battery A. The higher voltage of battery Bovercomes the potential of low voltage battery A, and current flows inthe direction in which the circuit was traced. The impulsesintermittently sent successively operate counting relays in thewellknown manner to operate a device for indicating to the operator theclass of service to which the calling subscriber is entitled. Thecounting relays and indicating device controlled by relay 206 may besimilar in construction and operation to those described in Patent No.1,200,788, issued October 10, 1916, to S. B. \Villiams, Jr. Relay 206has a high resistance winding and the lamp 8 is not lighted at thistime. The operator by depressing key 205 may complete a circuitfrom highvoltage battery B, resistance 207, key 205, operators sequence switchcontact 204, terminal 129, brush 125, conductor 136, connecting cordsequence switch contacts 135 and 140, left-hand armature and frontcontact of relay 139, conductor 118, brush 106, terminal 111, conductor9, lamp 8, contact 3, low voltage battery A, to ground. This circuitwill be intermittently completed by the operation of contacts 3 and 6,the object of the lamp 8 being to inform the operator of the number ofthe calling subscriber, if for any reason she wishes to checkthisinformation.

The operator then extends the connection to the wanted subscriber bymeans of a con-- nector switch whose brushes are indicated at 300 and301, the connector being of any wellknown type.

When the called subscriber answers, the operator is informed of hisanswering by means of a well-known supervisory signal (not shown) anddepresses a key208 to con trol the message register device operated bythe magnet 15. When the key 208 is depressed, acircuit is closed for arelay 209 from grounded battery, winding of relay 209, and key 208 toground. Relay 209, in attracting its armature, connects battery directlyto terminal 131'instead of through the resistance of the winding ofrelay 203. The increased current flow allows the marginal relay 1.5controlling the message register device to operate and the call isrecorded.

At the completion of conversation, the operator is informed by theoperation of wellknown supervisory signals that both subscribers havereplaced their receivers. The operator then depresses key 215 tocomplete a circuit from grounded battery, power magnet of sequenceswitch 210, contact 216, closed contacts of key 215 to ground, formoving the oper ators sequence switch out of position 7. Then theoperators sequence switch leaves position 7, the holding circuit ofrelay 139 is broken and relay 139 is cleenergized. Relay 139 in fallingoff completes a circuit from ground, right-hand armature and backcontact of relay 139, connecting cord sequence switch contact 141, andthe winding of power magnet 100 to battery, for moving the connectingcord sequence switch SS out of position 14 and into position 15. Inposition 15 a circuit is com pleted from grounded battery, through thewinding of down-drive magnet 142, conductor 143 and sequence switchcontact 144, to ground. Under the control of magnet 142 the line finderbrush carriage is moved downward. On arrivingin its normal position, acircuit is completed from ground, a brush 145, conducting segment 146,conductor 147, sequence switch contact 148 and the winding of powermagnet 100, to grounded battery, for moving the connecting cord sequenceswitch out of position 15 and into position 16. In position 16, acircuit is completed from grounded battery, downdrive magnet 149,sequence switch contact 150, to ground. Under the control of thedowndrive magnet the brush set of the cord selector CS is returned tonormal. On its arrival in normal position, a circuit is completed fromground through a brush 151, a conducting segment 152, conductor 1523,sequence switch contact 15% and the winding of ower magnet 100, togrounded battery, for moving the sequence switch SS from position 18 toposition 1. The connecting cord circuit is now restored to normal and isready to receive another call.

he operators cord circuit is restored to condition for receiving a callin a wellknown manner which it has not been con sidered necessary todescribe.

\Vhat is claimed is:

1. In a telephone exchange system, the combination with a connectingcircuit provided at its incoming end with a switch for establishingconnection to a calling line, and at its outgoing end with a switch forextending the connection, of a single relay for controlling the huntingoperation of either one or both of said switches.

2. In a telephone exchange system, the combination with a connectingcircuit provided at its incoming end with a switch for establishingconnection to a calling line, and at its outgoing end with a switch forextending the connection, of a single relay for controlling the huntingoperation of either one or both of said switches, and means fortransferring the test circuit of said relay from the first of saidswitches to the second of said switches.

3. In a telephone exchange system, the combination with a connectingcircuit pro vided at its incoming end with a switch for establishingconnection to a calling line, and at its outgoing end with a switch forextending the connection, of a device for indicating to an operator theclass of service to which a calling subscriber is entitled, and a testrelay common to said switches.

In a telephone exchange system, a connecting circuit provided at itsincoming end with a switch for establishing connection to a callingline, and at its outgoing end with a switch for extending theconnection, subscribers lines terminating in a contact bank of the firstof said switches, a brush carriage for the first of said switches, adevice for indicating to an operator the class of service to which thecalling subscriber is entitled, a test relay common to both of saidswitches, and means to prevent the energization of said. relay at thetime the finder brush set is passing over the terminals of a line whoseclass oi service indicating device is operating.

5. In a telephone exchange system, a connecting circuit provided at itsincoming end with a switch for establishing connection to a callingline, and at its outgoing end with a switch for extending theconnection, subscribe-rs lines terminating in a contact bank of thefirst of said switches, a brush carriage tor the first of said switches,a device for indicating to an operator the class of service to which thecalling subscriber is entitled, a test relay common to both of saidswitches, and a double winding for said relay, the magnetic effect ofsaid windings being differential to prevent the energization of saidrelay when a brush set passes over the terminals of a line at theinstant the class of service indicating device of such line isoperating.

in a telephone exchange system, a connecting circuit provided at itsincoming end with a switch for establishing connection to a callin line,and at its outgoing end with a switch for extending the connection,subscribers lines terminating in a contact bank or the first of saidswitches, a brush carriage for the first of said switches, centeringbrushes for said switches, commutator segments to be traversed by saidcentering brushes, said centering brushes being in electrical connectionwith a conducting segment at the time a brush set is positioned on theterminals of a calling line, a device for in dicating to an operator theclass of service to which the calling subscriber is entitled, a testrelay common to both of said switches, said relay having a doublewinding, the circuit oi? one of said windings extending through thecentering brush of whichever of said switches is operating, means forcausing the magnetic effect of said windings to be differential when thebrush set is passing the terminals of an undesired line, and means forcausing the magnetic effect of said windings to be cumulative when thebrush set arrives on the terminals of a calling line.

In witness whereof, I hereunto subscribe my name this 3rd day of July,A. D. 1916.

ALBEN E. LUNDELL.

Copies of this patent may be obtained for five cents each, by addressingthe Commissioner of Patents. Washington, D. G.

